Here is the full list of all 18 OTXO achievements.
Destroy the Heart
Kill 15 enemies with doors without dying
Kill an enemy with a thrown magazine
Kill 50 enemies with grenades
Clear a room without using Focus
Order the ANIMAL drink at the bar
Roll over 100 times
Die for the first time
Go fishing
Play fetch
Collect all guns
Collect everything from the gachapon machines
Vault over 50 times
Clear a room by only kicking
Clear a run on Impossible Mode
Kill 50 enemies with kunai
Unlock all drinks
Clear a full run without taking any drinks